Hot plug is a technology that allows a user to remove or replace, when a system is not shut down or powered off, a Peripheral Component Interconnect Express (PCIe) device mounted in downstream of a host, without affecting running of a host server system, so that a timely redundancy capability, expansibility, flexibility, and the like of the system are improved. At present, a hot plug function is critical to maintaining “high availability” of a PCIe system.
An existing hot plug technology is mainly as follows: After it is detected that a user triggers hot plug, an indicator is controlled to blink. Then, a PCIe bus is used to instruct a driver of a PCIe device to stop transmitting data, a link (connection) between the PCIe device and a slot is disrupted, and the slot is powered off. In this way, the physical connection between the PCIe device and the slot is in a high-impedance state, the indicator is off, the user removes the device, and hot removal is completed.
Because the data transmission based on the PCIe bus is distance-limited, the PCIe device can be used only in a limited short distance. The existing hot plug technology is hot plug in this scenario. As a requirement for using the PCIe device increases, currently, the PCIe device is remotely used. For example, a PCIe bridge device is used to cascade a PCIe device, PCIe data is carried in another transmission protocol for transmission, the PCIe device is moved far away, and a physical distance between the PCIe device and a host server exceeds a PCIe signal transmission distance threshold specified by the PCIe protocol.
Existing hot plug is specific only to a short-distance PCIe device. There is neither a device nor a function for performing hot plug on a remotely used PCIe device.